This disclosure relates to a directional microphone integrated into a case for a device.
Hearing assistance devices generally require microphones to receive acoustic inputs (e.g. speech) in the environment of the user for reproduction by the device. In most examples, the microphones are integrated into the user's ear-worn hearing assistance device. In other examples, generally as an accessory, one or more microphones or microphone arrays are located in a portable electronic device that the user may wear on a lanyard or place on a table, or ask the person to which they are speaking to wear it themselves. These devices often have selectable microphone directivity modes, such as omnidirectional for picking up all sounds in the environment or at least all speakers around a table, and directional which uses a microphone array for selective reception of sound from a specific direction, generally intended to receive voices of target talkers while receiving less noise from others sources. Although significant signal-to-noise ratio (SNR) gains may be realized by such an accessory, particularly if the speaking person is in close proximity (e.g. willing to wear it), using such a device is more invasive to target talkers relative to user-worn microphones in a hearing assistance device. Users must carry this additional piece of electronics and ask a talker to wear the device or at least talk towards it, for example. These and other complications such as cost and stigma result in low rates of adoption.
In other examples, the microphone of a smart phone or other personal computer may be used to provide audio to a hearing assistance device paired to the smart phone, but these do not provide directional microphone processing and an associated high-SNR signal for sound sources such as a conversation partner. One proposal to improve on this, by the current inventors, was a smart phone case that included an array of eight microphones around the perimeter, as described in U.S. Patent Application Publication 2015-0230026, the entire contents of which are incorporated here by reference. Three microphones on each of the left and right side combined with single microphones at the top and bottom edge to provide directional binaural microphone signals.
In 2010, Bose Corporation of Framingham Mass. introduced a new type of loudspeaker, described in U.S. Pat. No. 8,351,630, incorporated here by reference. This speaker uses a long, tapered tube with a slot along its length covered by a resistive screen to create an extremely directional output sound field from a single acoustic driver, and was used to provide surround sound signals from a centrally-located device, such as a television or sound bar. U.S. patent application Ser. No. 14/674,072, filed Mar. 31, 2015, and titled Directional Acoustic Device, incorporated here by reference, disclosed additional shapes the directional loudspeaker could take, and disclosed that replacing the acoustic driver with a microphone converted the device into a highly-directional microphone.